1. Field of the Invention
The present invention relates to solid powder cosmetics including make-up cosmetics such as foundations, face powders, eyebrows, eyeshadows, eyeliners, blushes, and powders, and powder washes and facial washes, and to a cosmetic which has a spherical, smooth surface, and which accomplishes smooth and uniform spread and a dry feel by blending resin particles having a uniform particle size.
2. Description of the Related Art
Conventionally, solid powder cosmetics have been widely used as cosmetics for correcting facial marks such as pimples, wrinkles, or pores and for adding shadow to lines on a face. However, if a large amount of a cosmetic is applied in order to enhance an effect such as coloring or covering, the applied layer becomes thick, increasing the likelihood that the makeup will create an unnatural impression and cause irregularity in color. These are significantly evident when spreading during application was not performed well. Further, in a recent trend, there has been an increasing desire that the cosmetics provide a natural finish. The natural finish is accomplished by forming a thin and uniform cosmetic-applied layer on the skin.
Fine particle cosmetics, which are normally formed into metal plates and the like to be used, are desired not only their characteristics as cosmetics but also for their formability. In other words, in addition to the characteristics as the makeup cosmetics accomplished by having smooth spread in only a small amount and being applied uniformly, it is desired that the cosmetics do not detach or crack when formed, and they can easily be adhered to small tools such as a sponge or a mat.
However, with conventional fine particle cosmetics, the cosmetics are easily detached or cracked, and additives must be added to achieve satisfactory formability.
Generally, the conventional fine particle cosmetics are compressed and formed to be filled into metal plates. In order to enhance the formability, methods have been applied including a method of including large amounts of additives such as oil solutions or adhesive components, a method of blending special oil components (Japanese Patent Publication Laid-open No. 2000-119134), a method of blending a specific binder resin (Japanese Patent Publication Laid-open No. 8-165221), and a method of agglutinating the fine particles with heat (Japanese Patent Publication Laid-open No. 11-228336). However, the problems of the cosmetics in which a large amount of oil solution components is blended include that they do not readily adhere to the sponge when used and that they are not smooth after use. Also, when the resin is aggregated after formation using heat, a feeling of discomfort commonly results due to the presence of the aggregated particles.
On the other hand, studies have shown that smooth spreading and an appropriate feeling of adhesion, which are desired in powder makeup cosmetics, depend upon physico-chemical properties such as the shape of materials blended into the cosmetics, a particle size distribution, surface conditions and hardness.
In recent studies, application properties and uniformity are improved through use of particles characterized by a certain primary particle size and a low span (a value found by the following equation from the particle sizes D90, D10 and D50 whose integrated values of the particle size distributions are equivalent to 90%, 10% and 50%; span=(D90−D10/D50) (Japanese Patent Publication Laid-open No. 8-277208), and with the particles whose particle size distribution (CV value) is within a certain range (Japanese Patent Publication Laid-open No. 2001-151639). Also, research has been conducted on the foundations rich in translucency enabled by keeping a prismatic reflectivity in a certain condition (Japanese Patent Publication Laid-open No. 11-209243).
Furthermore, many powder washes, especially facial washes, have recently been commercialized, and these washes are expected to have compatibility between spreadability that does not give the feeling of discomfort on the skin and appropriate massage effects. Spherical synthetic macromolecules are sometimes used as part of a feel improver or base materials in these washes.
The conventional cosmetics would include those that contain spherical polystyrene, nylon, polyacrylic, polyethylene, silicone, urethane and the like that are produced by an emulsion polymerization aggregation method, a suspension polymerization method or a precipitation polymerization method. However, because the particle size distributions of these spherical particles are wide and the surface conditions of the particles are not controlled, there has been a desire for development of cosmetics superior in spreadability when applied and superior in their formation of a uniform cosmetic layer.
Fine particle cosmetics, which have superior formability for deterring detachment or cracking of the cosmetics while restricting the use of the additives such as the oil solution components mention above to a small amount, have been especially desired.